See the movies

The following movies explore these themes are available for planetarium domes and for home DVD:

You might know someone who broke her leg. She went to the hospital, where a doctor took an x-ray, made sure that the ends of the bone fit together, then put a cast on. The cast stayed on for six weeks to protect the break so that it healed correctly. When a bone is broken, so are the blood vessels inside. These bleed, making a clot around the break. Special cells in the clot clean the break and form cartilage, the same as the bendable stuff in your nose and ears. Another kind of cell then moves into the break to eat up the cartilage, while still another kind of cell forms new bone. The new bone is just as strong as the bone was before it broke.